Why I state that it is not in our head is because there have been numerous examples of people knowing what others were doing around or near them while they were unconscious or otherwise not privy to someone else's conversations or situations. Yet many of these people wake up knowing things that they could not have known.
This anecdotal evidence has been suggested many times. WHAT PROOF that such experiences are actual and not fabricated or mistold? Site an actual case where some kind of actual affidavits are available that would be acceptable in a court of law as eyewitness accounts.
I read where people knew what was in the room while they were unconscious or what people were saying. I have never read where that was properly documented and it wasn't just some vague testimony. Without better documentation, it is no different than making bold ties to current events from vague things written by Nostradamus.
Even one of the most widely known/documented cases of a NDE does not offer solid testimony and there is controversy over whether the patient's experiences were caused during a time while she was alive.
http://en.wikipedia.org/wiki/Pam_Reynolds_case
I challenge that most other cases are totally bull crap made up based on the above or similar stories.